Boko Haram has released at least 80 schoolgirls kidnapped in 2014 from the northern Nigerian town of Chibok in exchange for members of the militant group held by authorities, the Nigerian presidency says.

Key points:

276 schoolgirls were abducted by Boko Haram in Chibok in 2014

Girls released in exchange for "some Boko Haram suspects" held by authorities

Release follows years of negotiations between Government and extremist group

It is the largest group of girls yet to be freed after years of tense negotiations.

"After lengthy negotiations, our security agencies have taken back these girls, in exchange for some Boko Haram suspects held by the authorities," the Government said in a statement posted to Twitter.

Switzerland and the International Committee of the Red Cross assisted in "lengthy negotiations" with the extremist group, the Government said, thanking them for their help.

Family members said they were eagerly awaiting a list of names and their "hopes and expectations are high".

The schoolgirls released today are expected to meet President Muhammadu Buhari soon.

The girls were taken from a school in the remote north-eastern Borno state, where Boko Haram has waged an insurgency aimed at creating an Islamic state that has killed thousands and displaced more than 2 million people.

At least 2,000 boys and girls have been kidnapped by Boko Haram since 2014, with many used as cooks, sex slaves, fighters and even suicide bombers, according to Amnesty International.

The use of children as suicide bombers by Boko Haram is also on the rise in the Lake Chad region, with 27 such attacks recorded in the first three months of 2017 compared to nine for the same period in 2016, the UN children's agency UNICEF said.

Despite having lost most of the territory it held in 2015, Boko Haram continues to wage its insurgency, which is now in its eighth year.